Heterologous polyclonal antibodies might represent an alternative to the use of convalescent plasma or monoclonal antibodies (mAbs) in coronavirus disease (COVID‐19) by targeting multiple antigen epitopes. However, heterologous antibodies trigger human natural xenogeneic antibody responses particularly directed against animal‐type carbohydrates, mainly the N‐glycolyl form of the neuraminic acid (Neu5Gc) and the α1,3‐galactose, potentially leading to serum sickness or allergy. Here, we immunized cytidine monophosphate‐N‐acetylneuraminic acid hydroxylase and α1,3‐galactosyl‐transferase (GGTA1) double KO pigs with the Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike receptor binding domain to produce glyco‐humanized polyclonal neutralizing antibodies lacking Neu5Gc and α1,3‐galactose epitopes. Animals rapidly developed a hyperimmune response with anti‐SARS‐CoV‐2 end‐titers binding dilutions over one to a million and end‐titers neutralizing dilutions of 1:10 000. The IgG fraction purified and formulated following clinical Good Manufacturing Practices, named XAV‐19, neutralized spike/angiotensin converting enzyme‐2 interaction at a concentration <1 μg/mL, and inhibited infection of human cells by SARS‐CoV‐2 in cytopathic assays. We also found that pig GH‐pAb Fc domains fail to interact with human Fc receptors, thereby avoiding macrophage‐dependent exacerbated inflammatory responses and a possible antibody‐dependent enhancement. These data and the accumulating safety advantages of using GH‐pAbs in humans warrant clinical assessment of XAV‐19 against COVID‐19.

Perfusion of convalescent plasma (CP) has demonstrated a potential to improve the pneumonia induced by SARS-CoV-2, but procurement and standardization of CP are barriers to its wide usage. Heterologous polyclonal antibodies of animal origin have been used to fight against infectious agents and are a possible alternative to the use of CP in SARS-CoV-2 disease. However, heterologous polyclonal antibodies trigger human natural xenogeneic antibody responses particularly directed against animal-type carbohydrate epitopes, mainly the N-glycolyl form of the neuraminic acid (Neu5Gc) and the Gal alpha1,3-galactose (a-Gal), ultimately forming immune complexes and potentially leading to serum sickness or allergy. To circumvent these drawbacks, we engineered animals lacking the cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) and alpha1,3-galactosyltransferase (GGTA1) enzymes to produce glyco-humanized polyclonal antibodies (GH-pAb) lacking Neu5Gc and a-Gal epitopes. We also found that these IgG Fc domains fail to interact with human Fc receptors and thereby should confer the safety advantage to avoiding macrophage dependent exacerbated inflammatory responses or elicit antibody-dependent enhancement (ADE), two drawbacks possibly associated with antibody responses against SARS-CoV-2. Therefore, we immunized CMAH/GGTA1 double knockout (DKO) pigs with the SARS-CoV-2 spike receptor binding domain (RBD) domain to elicit neutralizing antibodies. Animals rapidly developed hyperimmune sera with end-titers binding dilutions over one to a million and end-titers neutralizing dilutions of 1:10,000. The IgG fraction purified and formulated following clinical Good Manufacturing Practices, named XAV-19, neutralized Spike/ACE-2 interaction at a concentration < 1microgram/mL and inhibited infection of human cells by SARS-CoV-2 in cytopathic assays. These data and the accumulating safety advantages of using glyco-humanized swine antibodies in humans warrant clinical assessment of XAV-19 to fight against COVID-19.

No abstract

The control of antibody specificity plays pivotal roles in key technological fields such as diagnostics and therapeutics. During the development of immunoassays (IAs) for the biosensing of pathogens in food matrices, we have found a way to rationalize and control the specificity of polyclonal antibodies (sera) for a complex analytical target (the Salmonella genus), in terms of number of analytes (Salmonella species) and potential cross-reactivity with similar analytes (other bacteria strains). Indeed, the biosensing of Salmonella required the development of sera and serum mixtures displaying homogeneous specificity for a large set of strains showing broad biochemical variety (54 Salmonella serovars tested in this study), which partially overlaps with the molecular features of other class of bacteria (like specific serogroups of E. coli). To achieve a trade-off between specificity harmonisation and maximization, we have developed a strategy based on the conversion of the specificity profiles of individual sera in to numerical descriptors, which allow predicting the capacity of serum mixtures to detect multiple bacteria strains. This approach does not imply laborious purification steps and results advantageous for process scaling-up, and may help in the customization of the specificity profiles of antibodies needed for diagnostic and therapeutic applications such as multi-analyte detection and recombinant antibody engineering, respectively.

No abstract